1. Field of the Invention
This invention relates to a medical table for examination of the spine and for other diagnostic and therapeutic back procedures, and more particularly to a table which is adapted for use with an imaging device.
2. Description of the Prior Art
Tables of this type are used for various surgical and other medical procedures, such as lumbar and thoracic discography, including the injection of enzymes, cortisone, procaine or other analgesics, and contrast media. Such tables may also be used for electromyography, electrostimulation, proctology, rhizolysis and various other procedures.
When such tables are used for discography, electromyography, and other procedures in which injections are being performed or when probes or electrodes are being inserted, it is necessary that the location of the injection, probe, or electrode be precise in order to avoid the nerve bundles which are adjacent to the spine. Fluoroscopy, or some other imaging technique, may be used to monitor the position of the injection, probe, or electrode so that it can be performed precisely.
Recently, the use of chymopapain has been approved for injection into the lumbar discs to relieve the problems associated with herniated discs. As this procedure becomes more popular, the use of such surgical tables may increase.
U.S. Pat. No. 3,197,198, issued to John S. Collis, describes such a medical table in which the patient-supporting table top had a convex surface, so that when the patient was placed on the table, the patient's spine was in a maximally flexed condition. The table top was supported by a pair of side frames, one on each side. Each side frame consisted of a vertical forward leg and a forwardly inclined rearward leg which was longer than the forward leg. An upper side rail joined the two legs together and extended along the top of the table to complete the side frame. The patient was positioned on the table, with the patient's knees resting on a vertically adjustable platform. The adjustment of the platform was operated by a handwheel located at the front of the table which was connected to the platform by a rotatable rod which extended across the table beneath the table top.
While the medical table described in U.S. Pat. No. 3,197,198 represented a substantial improvement over previous tables, it had several disadvantages. The table was entirely suitable for making anterioposterior radiological images, but presented problems when taking lateral views and was unsatisfactory for taking oblique views because of the construction of the side frame. The side frame, which included a member running across the top of the table, was radiopaque and produced a shadow in views taken other than anterioposteriorally. In lateral views, the side frames produced a shadow which, depending upon the positioning of the patient, might not interfere with observation of the spine. However, in oblique views, the shadow produced by the side frame could interfere with a clear observation of the spine. Thus, oblique radiological views were not practical using this table, and tomography was very difficult or impossible.
Another problem with the aforementioned table was in the operation of the adjustable knee platform. Although the vertically adjustable knee platform was a convenience in adjusting the patient properly on the table top, the operating handwheel was located at the front of the table, which was inconvenient to the physician and the medical attendants who judged the positioning of the patient at the rear end of the table. Thus, it was necessary for the physician or the medical attendants to observe the positioning of the patient on the table, to walk around to the front of the table to adjust the handwheel and subsequently to return to the back of the table to reposition the patient. This procedure was often repeated several times before the patient was properly positioned on the table. In addition, the rotatable rod which connected the handwheel to the adjusting mechanism for the knee platform extended longitudinally across the length of the table and could possibly interfere with the portion of an imaging device which was placed beneath the table top.